1. Field of the Invention
The present invention relates to a packing material fitting structure such that the packing material can be prevented from easily separating or dropping out of a fitting groove in a packing material fitting place in a part such as a casing or a cover of an engine or a pump with sealing property, the packing material can be easily mounted and fixed, and the sealing ability in the packing material fixing place can be prevented from decreasing.
2. Description of the Related Art
Packing materials have been widely used in portions requiring sealing ability in parts such as casings and covers of engines, pumps, and the like. An annular (loop-shaped) groove is formed in a joining surface to mount the packing material between the joining surfaces of structural members such as casings and covers, and a packing material of a similar annular shape is mounted along the longitudinal direction of the fitting groove. In most cases, once a predetermined assembling operation of this part is completed, the part is transported to another site and mounted on a large structural object such as an engine.
A problem arising in this case is that during handing and transportation to another assembling site or the like, and before mounting on a structural object etc., the packing material can drop out of the structural member and be lost or the packing material can separate in the assembling operation, thereby decreasing operation efficiency. In order to prevent the packing material from easily separating and dropping out of the fitting groove of the casing, protrusions have been formed with an appropriate spacing in the longitudinal direction of the packing material to maintain the mounted state thereof. These protrusions are caught in the fitting groove and prevent the packing material from separating and dropping out of the fitting groove of the casing during the assembling operation or during transportation.
As a means for resolving the above-described problems, protrusions have been formed in several locations on the inner wall of the fitting groove and the packing material has been pushed against and fixed to the opposing inner wall with the protrusions, thereby preventing the packing material from dropping out. However, a variety of problems arise when the protrusions are formed without forethought at the inner wall of the fitting groove. For example, where the protrusions are small, a fixing force sufficient to fix the packing material inside the fitting groove cannot be obtained and the packing material drops out easily from the fitting groove.
Where the protrusions are large, a pressing force that fixes the packing material increases and a sufficient force for fixing the packing material can be obtained. However, in this case, the cross section of packing material deforms in the protrusion formation places, torsion occurs in the packing material, and the packing material can rise. Where the packing material in this state is fitted in another structural body, the packing material projects from the fitting groove, the projecting portion is cut into and crushed in the joining surface place of the other part, and sealing capacity of the packing material is degraded. A structure resolving the above-described problems is disclosed in Japanese Patent Application Laid-open No. 2005-233315.
The invention disclosed in Japanese Patent Application Laid-open No. 2005-233315 can resolve most of the conventional problems, but there is still space for improvement. First, when a casing is mounted on a cover or another device and an assembled state is produced, there is a risk of the packing material projecting from the inner side (or outer side) in the transverse direction of the fitting groove to the outside of the fitting groove. As a result, the degree of freedom in designing a pump space and, therefore, the degree of freedom in designing a casing shape can be restricted. Furthermore, because the packing material is fixed to the fitting groove by fitting the projection of the packing material into the cutout portion, a large tightening force is required, in particular to attain strong fitting of the projection and the cutout portion, and a large load is placed on a worker.